Vehicle auxiliary pump control

ABSTRACT

A vehicle includes a main pump and an auxiliary pump, each configured to provide fluid to a hydraulic circuit. A motor is configured to drive the auxiliary pump. A controller is configured to determine a temperature of the motor, compare the temperature of the motor to a first predetermined operating threshold, and disable the auxiliary pump and enable the main pump if the temperature of the motor is above the first predetermined operating threshold. A method of controlling fluid flow in the vehicle includes determining a temperature of the motor, comparing the temperature to the first predetermined operating threshold, and disabling the auxiliary pump and enabling the main pump if the temperature of the motor is above the first predetermined operating threshold.

TECHNICAL FIELD

The invention relates to control of the use of an auxiliary pump in avehicle.

BACKGROUND

Passenger and commercial vehicles may use pumps driven by an engine ormotor to provide fluid to various hydraulic devices in the vehicle. Forexample, the engine and/or motor may drive one or more pumps byproviding a torque to the pump. The pump, in turn, provides pressurizedfluid to hydraulic devices in the vehicle in accordance with the torqueprovided by the engine and/or motor.

SUMMARY

An example vehicle includes a main pump, an auxiliary pump, a motor, anda controller. The main pump and the auxiliary pump are each configuredto provide fluid to a hydraulic circuit. The motor is configured todrive the auxiliary pump. The controller is configured to determine atemperature of the motor and compare the temperature of the motor to afirst predetermined operating threshold. The controller is furtherconfigured to disable the auxiliary pump and enable the main pump if thetemperature of the motor is above the first predetermined operatingthreshold.

A method of controlling fluid flow in a vehicle includes determining atemperature of a motor driving the auxiliary pump, comparing thetemperature to a first predetermined operating threshold, and disablingthe auxiliary pump if the temperature of the motor is above the firstpredetermined operating threshold. The method also includes enabling amain pump if the temperature of the motor is above the firstpredetermined operating threshold.

The above features and the advantages and other features and advantagesof the present invention are readily apparent from the followingdetailed description of the best modes for carrying out the inventionwhen taken in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of an example vehicle configured tocontrol an auxiliary pump.

FIG. 2 is a flowchart of an example process that may be implemented tocontrol the auxiliary pump.

FIG. 3 is a flowchart of another example process that may be implementedto control the auxiliary pump.

DETAILED DESCRIPTION

A vehicle is provided with a main pump, an auxiliary pump, a motor, anda controller. The main pump and the auxiliary pump are each configuredto provide fluid to a hydraulic circuit. The motor is configured todrive the auxiliary pump. The controller is configured to determine atemperature of the motor and compare the temperature of the motor to afirst predetermined operating threshold. The controller is furtherconfigured to disable the auxiliary pump and enable the main pump if thetemperature of the motor is above the first predetermined operatingthreshold. Accordingly, the controller may prevent the motor fromfailing if the motor begins to overheat. The controller may be furtherconfigured to allow the motor to turn back on after the motor has hadtime to cool. This way, the controller may control the operation of theauxiliary pump to prevent the motor from overheating.

FIG. 1 illustrates a vehicle 100 able to determine whether a motor is indanger of overheating, and if so, take appropriate remedial action(e.g., disable an auxiliary pump). The vehicle 100 may take manydifferent forms and include multiple and/or alternate components andfacilities. While an example vehicle 100 is shown in the Figures, thecomponents illustrated in the Figures are not intended to be limiting.Indeed, additional or alternative components and/or implementations maybe used.

The vehicle 100 may include an engine 105, a motor 110, a temperaturesensor 115, a main pump 120, an auxiliary pump 125, a hydraulic circuit130, and a controller 135. The vehicle 100 may include any automobilehaving two pumps driven by different sources. For example, the vehicle100 may be any passenger or commercial automobile such as a hybridelectric vehicle including a plug-in hybrid electric vehicle (PHEV) oran extended range electric vehicle (EREV), a gas-powered vehicle, or thelike.

The engine 105 may include any device configured to generate torque froma fuel. For instance, the engine 105 may include an internal combustionengine configured to output torque via a crankshaft by burning a mixtureof fuel and air. In one possible implementation, the torque from theengine 105 may be output to a transmission or gearbox (not shown).Further, the torque from the engine 105 may be used to drive one or moreother devices, such as the main pump 120, which is described in detailbelow. Further, the operation of the engine 105 may be controlled by anengine control unit (not shown).

The motor 110 may include any device configured to convert electricalenergy into a torque. That is, the motor 110 may receive electricalenergy from a power source (not shown) such as a battery and provide atorque via an output shaft using the electrical energy. For example, themotor 110 may include a stator, a rotor, and a commutator. The statormay include any device configured to receive the electrical energy fromthe power source and generate a magnetic field with the electricalenergy. The rotor may include any device configured to rotate relativeto the stator when the stator is provided with the electrical energy.That is, the rotor may be configured to rotate in response to themagnetic field produced by the stator. The commutator may include anydevice configured to help the rotor maintain rotational motion, andthus, help the motor 110 provide torque. The output shaft may bedisposed on the rotor such that the rotor and the output shaft rotate atsubstantially the same speeds. In one possible approach, the motor 110may further act as a generator and store electrical energy in the powersource if, for example, the motor 110 is provided with a torque. Forexample, the engine 105 may provide the motor 110 with a torque by usinga belt (not shown) operably connected to the crankshaft of the engine105 and the output shaft of the motor 110. The operation of the motor110 may be controlled by a motor control unit (not shown).

The temperature sensor 115 may include any device configured to measurea temperature of the motor 110. The temperature sensor 115 may beoperatively disposed on or near the motor 110 and may be configured togenerate a signal representative of the temperature of the motor 110.For example, the temperature sensor 115 may be configured to directly orindirectly measure the temperature of the stator, the rotor, orelectronics used to drive the motor 110. In one possible implementation,the temperature of the motor 110 may be estimated without the use of thetemperature sensor 115 as discussed in further detail below.

The main pump 120 may include any device configured to provide fluid ata commanded pressure when provided with a torque. For instance, the mainpump 120 may be configured to receive the torque generated by the engine105 via the crankshaft and provide fluid at a pressure based on thetorque from the engine 105. Thus, the main pump 120 may be configured toprovide fluid at any time the engine 105 is enabled.

The auxiliary pump 125 may include any device configured to providefluid at a commanded pressure when provided with a torque. For instance,the auxiliary pump 125 may be configured to receive the torque generatedby the motor 110 via the output shaft and provide fluid at a pressurebased on the torque from the motor 110. Thus, the main pump 120 may beconfigured to provide fluid at any time the motor 110 is enabled.

The hydraulic circuit 130 may include any device configured to providefluid to one or more hydraulic components of the vehicle 100. Thehydraulic circuit 130, therefore, may include a valve body, one or morevalves, one or more clutch assemblies, etc., or any other hydraulicdevice configured to operate when provided with pressurized fluid. Thehydraulic circuit 130 may be operatively connected to the main pump 120,the auxiliary pump 125, or both. This way, the main pump 120, theauxiliary pump 125, or both, may provide fluid to the hydraulic devicesof the hydraulic circuit 130. Of course, the vehicle 100 may have anynumber of hydraulic circuits 130 operatively connected to one or both ofthe main pump 120 and the auxiliary pump 125.

The controller 135 may include any device configured to control variousaspects of the vehicle 100. For example, in some circumstances, thecontroller 135 may be configured to command the engine 105, motor 110,or both to turn on or off. For example, the controller 135 may beconfigured to command the motor 110 on and the engine 105 off when thepower source can supply a sufficient amount of electrical energy for themotor 110 or another motor (not shown) to propel the vehicle 100. If,however, the electrical energy stored in the power source drops below acertain level, the controller 135 may be configured to command theengine 105 to turn on to provide torque to the motor 110 to cause themotor 110 to generate electricity that may be stored in the powersource. Alternatively, the controller 135 may command the engine 105 toturn on to provide torque to a transmission (not shown) to propel thevehicle 100 directly. Accordingly, the controller 135 may controldifferent operating modes of the vehicle 100 based on whether the engine105, the motor 110, or both are commanded on.

The controller 135 may be further configured to command the motor 110and/or engine 105 on or off for reasons other than to propel the vehicle100. For example, the controller 135 may command the motor 110 on or offto control the operation of the auxiliary pump 125 and the controller135 may command the engine 105 on or off to control the operation of themain pump 120. The controller 135 may do so for various reasons, such asto reduce motor failure if the motor 110 driving the auxiliary pump 125becomes too hot.

In one possible approach, the controller 135 may be configured todetermine a temperature of the motor 110 and compare the temperature ofthe motor 110 to a first predetermined operating threshold, which mayrepresent the maximum temperature at which the motor 110 may operate.The controller 135 may be configured to receive the temperature measuredby the temperature sensor 115. Alternatively, the controller 135 mayestimate the temperature of the motor 110 based on various factors suchas the amount of current provided to the motor 110 from the powersource, the speed of the motor 110, the amount of torque generated bythe motor 110, etc.

If the temperature of the motor 110 is above the first predeterminedoperating threshold, the controller 135 may be configured to disable themotor 110 to disable the auxiliary pump 125 and enable the main pump 120to provide fluid to the hydraulic circuit 130. To disable the auxiliarypump 125, the controller 135 may be configured to transmit a controlsignal to the motor 110 that commands the motor 110 to turn off. Toenable the main pump 120, the controller 135 may be configured totransmit a control signal that commands the engine 105 to turn on.Additionally, the controller 135 may set a flag indicating that themotor 110 may not be commanded on despite other requests for torque fromthe motor 110. When the flag is set, the controller 135 may cause theengine 105 to generate the torque requested by the motor 110, includingthe torque to drive the main pump 120 to provide fluid to the hydrauliccircuit 130.

If the temperature falls below a second predetermined operatingthreshold, the controller 135 may be configured to allow the auxiliarypump 125 to be enabled. For example, the controller 135 may beconfigured to clear the flag and allow the motor 110 to provide torqueto the auxiliary pump 125. Clearing the flag may indicate that theauxiliary pump 125 is available for use. That is, once the flag isclear, the controller 135 may be configured to allow the main pump 120to be disabled (e.g., when the engine 105 is commanded off). However,the controller 135 need not immediately disable the main pump 120 andenable the motor 110 when the flag is clear. For example, the vehicle100 may be operating in an “engine only” mode (e.g., only the engine 105is commanded on to propel the vehicle) when the flag is cleared.Clearing the flag may allow the controller 135 to command the motor 110to turn on when the vehicle 100 is no longer operating in the “engineonly” mode. The first and second predetermined operating thresholds mayrepresent the same or different temperatures. If different temperatures,the controller 135 may give the motor 110 additional time to cool evenafter the temperature of the motor 110 has fallen below the firstpredetermined operating threshold.

In general, computing systems and/or devices, such as the controller135, the engine control unit, the motor control unit, etc., may employany of a number of computer operating systems and generally includecomputer-executable instructions, where the instructions may beexecutable by one or more computing devices such as those listed above.Computer-executable instructions may be compiled or interpreted fromcomputer programs created using a variety of well known programminglanguages and/or technologies, including, without limitation, and eitheralone or in combination, Java™, C, C++, Visual Basic, Java Script, Perl,etc. In general, a processor (e.g., a microprocessor) receivesinstructions, e.g., from a memory, a computer-readable medium, etc., andexecutes these instructions, thereby performing one or more processes,including one or more of the processes described herein. Suchinstructions and other data may be stored and transmitted using avariety of known computer-readable media.

A computer-readable medium (also referred to as a processor-readablemedium) includes any non-transitory (e.g., tangible) medium thatparticipates in providing data (e.g., instructions) that may be read bya computer (e.g., by a processor of a computer). Such a medium may takemany forms, including, but not limited to, non-volatile media andvolatile media. Non-volatile media may include, for example, optical ormagnetic disks and other persistent memory. Volatile media may include,for example, dynamic random access memory (DRAM), which typicallyconstitutes a main memory. Such instructions may be transmitted by oneor more transmission media, including coaxial cables, copper wire andfiber optics, including the wires that comprise a system bus coupled toa processor of a computer. Common forms of computer-readable mediainclude, for example, a floppy disk, a flexible disk, hard disk,magnetic tape, any other magnetic medium, a CD-ROM, DVD, any otheroptical medium, punch cards, paper tape, any other physical medium withpatterns of holes, a RAM, a PROM, an EPROM, a FLASH-EEPROM, any othermemory chip or cartridge, or any other medium from which a computer canread.

FIG. 2 illustrates an example process 200 that may be implemented by thecontroller 135 to control the use of the auxiliary pump 125 to, forexample, protect the motor 110 from overheating.

At block 205, the controller 135 may determine the temperature of themotor 110. For example, the controller 135 may receive the signalgenerated by the temperature sensor 115 or estimate the temperaturebased on factors such as the amount of current provided to the motor 110from the power source, the speed of the motor 110, the amount of torquegenerated by the motor 110, etc.

At decision block 210, the controller 135 may compare the temperaturedetermined at block 205 to the first predetermined operating threshold.The first predetermined operating threshold may represent the maximumtemperature at which the controller 135 will allow the motor 110 tooperate before disabling the motor 110. If the temperature is below thefirst predetermined operating threshold, the process 200 may continue atblock 205. If the temperature is above the predetermined operatingthreshold, the process 200 may continue at block 215.

At block 215, the controller 135 may disable the auxiliary pump 125. Forexample, the controller 135 may command the motor 110 to turn off. Asdiscussed above, the torque provided by the motor 110 drives theauxiliary pump 125. Thus, commanding the motor 110 to turn off willdisable the auxiliary pump 125 and the process 200 may continue at block220.

At block 220, the controller 135 may enable the main pump 120 by, forinstance, commanding the engine 105 to turn on. As discussed above, thetorque provided by the engine 105 drives the main pump 120. Accordingly,commanding the engine 105 to turn on causes the main pump 120 to providefluid to the hydraulic circuit 130. As such, the hydraulic circuit 130may still receive fluid if the temperature of the motor 110 is above thefirst predetermined operating threshold.

FIG. 3 illustrates another example process 300 that may be implementedby the controller 135 to control the use of the auxiliary pump 125 to,for example, protect the motor 110 from overheating.

At block 305, the controller 135 may determine the temperature of themotor 110. For example, the controller 135 may receive the signalgenerated by the temperature sensor 115 or estimate the temperaturebased on factors such as the amount of current provided to the motor 110from the power source, the speed of the motor 110, the amount of torquegenerated by the motor 110, etc.

At decision block 310, the controller 135 may compare the temperaturedetermined at block 305 to the first predetermined operating threshold.As previously discussed, the first predetermined operating threshold mayrepresent the maximum temperature at which the controller 135 will allowthe motor 110 to operate before disabling the motor 110. If thetemperature is below the first predetermined operating threshold, theprocess 300 may continue at block 305. If the temperature is above thepredetermined operating threshold, the process 300 may continue at block315.

At block 315, the controller 135 may set a flag indicating that themotor 110 may not be commanded on despite requests for torque from themotor 110. Therefore, the controller 135 and other electronic devicessuch as the motor control unit may be unable to command the motor 110 toturn on when the flag is set. Further, setting the flag may furtherindicate that the auxiliary pump 125 is not available for use.

At block 320, the controller 135 may command the motor 110 to turn off.As discussed above, commanding the motor 110 to turn off may cause theauxiliary pump 125 to cease providing fluid to the hydraulic circuit130. Additionally, turning the motor 110 off will allow the motor 110 tocool.

At block 325, the controller 135 may command the engine 105 to turn onto, for example, drive the main pump 120 and provide fluid to thehydraulic circuit 130. As discussed above, the flag set at block 315 mayindicate that the auxiliary pump 125 is not available for use. Thecontroller 135 may command the engine 105 on and thus enable the mainpump 120 to provide fluid to the hydraulic circuit 130 so that thehydraulic circuit 130 may still operate despite the temperature of themotor 110.

At block 330, the controller 135 may determine the temperature. Forinstance, the controller 135 may estimate the temperature of the motor110 or receive the measured temperature from the temperature sensor 115.

At decision block 335, the controller 135 may compare the temperaturemeasured at block 330 to the second predetermined operating threshold.The second predetermined operating threshold may represent a temperatureat which the motor 110 may be enabled without significant risk ofoverheating. If the temperature measured at block 330 is above thesecond predetermined operating threshold, the process 300 may continueat block 330. If, however, the temperature of the motor 110 measured atblock 330 is below the second predetermined threshold, the process 300may continue at block 340.

At block 340, the controller 135 may clear the flag to allow the motor110 to turn on to drive the auxiliary pump 125. Clearing the flag mayindicate that the auxiliary pump 125 is available for use. That is, oncethe flag is clear, the controller 135 may allow the main pump 120 to bedisabled (e.g., when the engine 105 is commanded off). However, thecontroller 135 need not immediately disable the main pump 120 and enablethe motor 110 when the flag is clear. For example, the vehicle 100 maybe operating in an “engine only” mode (e.g., only the engine 105 iscommanded on to provide torque to the wheels) when the flag is cleared.Clearing the flag may allow the motor 110 to be commanded on when thevehicle 100 is no longer operating in the “engine only” mode.

While the best modes for carrying out the invention have been describedin detail, those familiar with the art to which this invention relateswill recognize various alternative designs and embodiments forpracticing the invention within the scope of the appended claims.

1. A vehicle comprising: a main pump configured to provide fluid to a hydraulic circuit; an auxiliary pump configured to provide fluid to the hydraulic circuit; a motor configured to drive the auxiliary pump; and a controller configured to determine a temperature of the motor, compare the temperature of the motor to a first predetermined operating threshold, and disable the auxiliary pump and enable the main pump if the temperature of the motor is above the first predetermined operating threshold.
 2. A vehicle as set forth in claim 1, further comprising a sensor configured to measure the temperature of the motor.
 3. A vehicle as set forth in claim 1, wherein the controller is configured to estimate the temperature of the motor.
 4. A vehicle as set forth in claim 1, wherein the controller is configured to allow the auxiliary pump to be enabled if the temperature of the motor falls below a second predetermined operating threshold.
 5. A vehicle as set forth in claim 4, wherein the first predetermined operating threshold and the second predetermined operating threshold each represents a different temperature.
 6. A vehicle as set forth in claim 1, further comprising an engine configured to provide a torque to drive the main pump.
 7. A vehicle as set forth in claim 1, wherein the motor is configured to provide a torque to drive the auxiliary pump.
 8. A vehicle as set forth in claim 1, wherein the controller is configured to disable the auxiliary pump by generating a control signal that commands the motor to turn off.
 9. A vehicle as set forth in claim 1, further comprising an engine configured to drive the main pump, and wherein the controller is configured to enable the main pump by generating a control signal that commands the engine to turn on.
 10. A method of controlling fluid flow in a vehicle, the method comprising: determining a temperature of a motor driving the auxiliary pump; comparing the temperature to a first predetermined operating threshold; disabling the auxiliary pump if the temperature of the motor is above the first predetermined operating threshold; and enabling a main pump if the temperature of the motor is above the first predetermined operating threshold.
 11. A method as set forth in claim 10, wherein disabling the auxiliary pump includes commanding the motor to turn off.
 12. A method as set forth in claim 10, wherein enabling the pump includes commanding an engine driving the main pump to turn on.
 13. A method as set forth in claim 10, further comprising allowing the motor to turn on to drive the auxiliary pump and allowing the main pump to be disabled if the temperature is below a second predetermined operating threshold.
 14. A method as set forth in claim 10, wherein determining the temperature of the motor includes measuring the temperature of the motor with a sensor.
 15. A method as set forth in claim 10, wherein determining the temperature of the motor includes estimating a temperature of the motor.
 16. A method as set forth in claim 10, wherein disabling the auxiliary pump includes setting a flag indicating that the auxiliary pump is not available for use.
 17. A method as set forth in claim 16, further comprising clearing the flag if the temperature of the motor is below a second predetermined operating threshold.
 18. A vehicle comprising: a main pump configured to provide fluid to a hydraulic circuit; an auxiliary pump configured to provide fluid to the hydraulic circuit; a motor configured to drive the auxiliary pump by providing a torque to the auxiliary pump; an engine configured to drive the main pump by providing a torque to the main pump; and a controller configured to determine a temperature of the motor, compare the temperature of the motor to a first predetermined operating threshold, and disable the auxiliary pump and enable the main pump if the temperature of the motor is above the first predetermined operating threshold, wherein the controller is configured to disable the auxiliary pump by commanding the motor to turn off and enable the main pump by commanding the engine to turn on; and wherein the controller is configured to allow the auxiliary pump to be enabled if the temperature of the motor falls below a second predetermined operating threshold.
 19. A vehicle as set forth in claim 18, further comprising a sensor configured to measure the temperature of the motor.
 20. A vehicle as set forth in claim 18, wherein the controller is configured to estimate the temperature of the motor. 